Understanding Risk Factors for Amputation in Patients With Diabetes and/or Peripheral Arterial Disease in a Highly Rural State

Abstract

Amputation is a devastating but prevenTable complication of diabetes and peripheral arterial disease (PAD). It is a marker of severe disease and of disparities in quality of care. Rural populations have multiple risk factors for amputation; however, there is a significant gap in amputation research in rural communities. This study sought to identify risk factors for amputation in the highly rural state of West Virginia using a large, longitudinal institutional database. The West Virginia Clinical and Translational Science Institute Integrated Data Repository, a longitudinal database of more than 2 million patients, containing electronic health record data for all inpatient and outpatient encounters at West Virginia University and West Virginia University-affiliated hospitals and clinics comprised the sample for analyses. Adults (≥18 years) with recorded diagnoses of diabetes and/or PAD between 2011 and 2016 were included based on International Classification of Diseases, 9th clinical modification, and 10th edition clinical modification codes. Major and minor amputations were identified using Current Procedural Terminology codes. Trauma patients were excluded. Descriptive analyses and multivariable logistic regression models examining factors associated with major, minor and any amputation were performed. During the study period, 50,276 patients were treated for diabetes and/or PAD, 369 (7.3/1000) had any amputation over the study period; 210 had major (4.2/1000) amputations, 128 had minor (2.5/1000) amputations and 31 patients had both (0.6/1000). On multivariable analyses (Table I), male sex, self-pay, Medicaid, and Medicare insurance status all had significantly higher risk for major amputation. Minor amputation, which is often considered protective for major amputation, was found to increase the odds of major amputation 11.7 times. PAD patients had 12.3 times higher odds of any amputation compared to patients with diabetes, while patients with both diabetes and PAD had a 51.8 times higher odds of any amputation compared to patients with diabetes alone. C-statistics for all models were over 0.8, indicating a strong model. This unique longitudinal dataset has allowed us to identify several important features of diabetes and PAD-related amputation in our patient population: the first is that West Virginians undergo amputation for diabetes and/or PAD at rates more than double (7.3/1000 compared to the national prevalence of 2.4/1000) the rest of the country. In addition, patients with PAD alone or PAD plus diabetes had strikingly higher odds for amputation compared to diabetes alone. This suggests that population-based interventions for amputation prevention may be more successful if focused on PAD risk factor modification, such as tobacco cessation and medical optimization, rather than just simple diabetic foot care measures.TableMultivariable analysis of odds of major, minor and any amputation in patients with diabetes and/or peripheral artery disease (PAD) in West VirginiaVariableMajor (adjusting for minor)Minor (excluding majors)Any amputationMinora11.79 (7.19-19.33)––Rural (defined using Rural-urban community area code)1.09 (0.8-1.48)0.82 (0.52-1.29)0.98 (0.77-1.27)Tobacco user0.91 (0.57-1.44)0.9 (0.48-1.71)0.9 (0.62-1.31)Male vs female2.15 (1.61-2.85)2.63 (1.77-3.9)2.43 (1.93-3.07)Medicaid vs private1.79 (1.18-2.71)0.88 (0.51-1.51)1.35 (0.98-1.87)Medicare vs private1.54 (1.04-2.26)0.7 (0.43-1.15)1.12 (0.83-1.52)Self-pay vs private1.83 (1.09-3.07)1.42 (0.76-2.66)1.69 (1.13-2.52)Age0.99 (0.98-1)0.99 (0.97-1.01)0.99 (0.98-1)CAD0.36 (0.27-0.49)0.18 (0.12-0.28)0.26 (0.2-0.33)PAD vs diabetes13.78 (7.75-24.49)8.4 (4.18-16.85)12.29 (7.93-19.07)PAD and diabetes vs diabetes41.07 (23.27-72.46)52.52 (27.43-100.53)51.81 (33.85-79.3)CHF1.11 (0.79-1.54)1.5 (0.94-2.38)1.24 (0.95-1.62)CKD1.83 (1.32-2.54)1.5 (0.95-2.36)1.75 (1.34-2.27)COPD0.99 (0.73-1.34)1.07 (0.7-1.64)1 (0.78-1.29)Hypercholesterolemia0.97 (0.73-1.3)0.76 (0.52-1.13)0.89 (0.71-1.13)Obesity0.92 (0.68-1.25)0.92 (0.61-1.4)0.93 (0.73-1.19)Renal failure1.47 (0.97-2.24)0.85 (0.43-1.7)1.24 (0.87-1.77)C-statistic0.8500.8160.841Text in bold indicates statistically significant findings.aFor those with both major and minor amputations, we only counted minors occurring before major to see if that led to higher odds of major amputations. Open table in a new tab